Victoria Toline needed nine months to taper off Zoloft. “I had to drop out of school,” she said. “My life’s been on hold.”Credit Ruth Fremson/The New York Times

Victoria Toline would hunch over the kitchen table, steady her hands and draw a bead of liquid from a vial with a small dropper. It was a delicate operation that had become a daily routine — extracting ever tinier doses of the antidepressant she had taken for three years, on and off, and was desperately trying to quit.

“Basically that’s all I have been doing — dealing with the dizziness, the confusion, the fatigue, all the symptoms of withdrawal,” said Ms. Toline, 27, of Tacoma, Wash. It…